1. Field of the Invention
The present invention relates to a tamper respondent covering, and, more particularly to a tamper respondent covering that protects data from a tampering operation by covering electronic parts such as, integrated circuits (ICs) that are embedded inside or exposed outside a product and contain data concerning security and certifications, and communication connectors that transmit data, etc. using a cover-shaped structure and by erasing important data stored in the electronic part to be protected or disabling the operation of the electronic part when it detects tampering of the electronic part to be protected, for example, when someone attempts to remove the tamper respondent covering from a printed circuit board (PCB) of the electronic part or to drill a hole in the tamper respondent covering for the purpose of hacking the data in the electronic part.
2. Description of the Related Art
Enclosures or covers that enclose electronic parts have the form of envelopes and shallow boxes with walls which are formed by folding flexible sheets incorporating tampering detection characteristics. The sheet includes layers of flexible material in which a matrix of semi-conductive lines printed on an insulating film is incorporated. The matrix of semi-conductive lines forms a continuous conductor which breaks if there is an attempt to penetrate the insulating film. Since a circuit in the enclosures or covers has a conductor, the circuit is monitored by opening the conductor and measuring the resistance between the two ends of the circuit. The flexible sheets are folded and overlapped to create a wedge-, cuboid-, or cube-shaped enclosure as disclosed in GB 258 075 A in which a laminate is folded about a plurality of fold lines to form an enclosure. U.S. Pat. No. 5,858,500 discloses an envelope- or a box-shaped flexible sheet which is set in a sellable material.
The enclosure is intended to surround an item to be protected, such as an electronic device which may be an encryption module, a chip, or a circuit for processing which stores or carries potentially valuable information. As noted above, all attempts to penetrate the enclosure result in damaging to one or more of the lines, which is detected by the change in the electrical characteristics of the conductor. Upon detecting such a change, the valuable information stored in the item is typically erased or destroyed, and an alarm may be activated.
It may however be relatively time-consuming and expensive to enclose and surround the item with such an enclosure. Also, the provision of an enclosure which completely surrounds an item restricts the manner in which the item may be located and positioned within a larger device and is likely to, for example, preclude conventional surface mounting.
US Patent Application Publication No. US2002/0002683 AI by Benson, et al. discloses a Security Module System that comprises a cover which encloses the components to be protected and abuts against the substrate, on which the components are mounted, using a ball grid array connection system. The cover comprises a serpentine pattern of metallic conductors which may be interconnected with a pattern of metallic conductors embedded in the substrate by a system of plated through-holes and blind vias to form a three dimensional array of conductors surrounding the components to be protected. To prevent the pattern and location of the metallic conductors from being detected by non-destructive techniques such as X-rays, back panels made of X-ray opaque material are laminated on the cover and the substrate.
Furthermore, to deter a chemical attack on the system, additional elements such as conductive ink fuses are provided on the substrate. The system disclosed has a number of shortcomings in relation to resistance to intrusive attacks, for example, the X-ray opaque back planes can be easily located and could be ground away or electrochemically etched, allowing the underlying pattern of metallic conductors to be exposed to X-rays or other non-destructive techniques. Areas of the metallic conductors could then be effectively bridged by attaching wire links to the serpentine pattern of conductors and the cover or substrate which was breached, without triggering the tamper respondent circuit.
Similarly, the vias in the side wall of the cover could be located and similarly bridged without triggering the tamper respondent circuit. The side walls are not protected by the pattern of serpentine conductors and therefore present an area susceptible to attack, as does the system of ball grid array interconnections.
It would also be possible by similar techniques to locate the positions of the conductive ink fuses on the circuit board and to direct a chemical attack at locations far away from the fuses without triggering a tamper response.
FIG. 1 illustrates a tamper respondent covering disclosed in PCT Publication No. WO2005/098950. In this patent document, the tamper respondent covering 10 is adapted for mounting on a surface having at least one item 3 and 4 disposed thereon, and the tamper respondent covering 10 includes a cover member defining a recess 7 and at least one non-metallic detecting element having an electrical characteristic disposed on the cover member. That is, the cover member is adapted for mounting on the surface and covering and protecting the at least one item 3 (and 4) on the surface such that damage to the at least non-metallic detecting element results in a detectable variation in the electrical characteristics.
The inventor of the present application invented a device that can reliably detect an external shock or attack even when the device is applied to any type of product by improving the technology disclosed in PCT Publication No. WO2005/098950.